NEW DELHI: India's telecom department has directed all internet service providers to advise customers to take necessary precautions to protect modems - instruments that connect a computer to the Internet - from malware attacks and hacking attempts.

In a directive issued to all internet service providers (ISPs) seen by ET, the telecom department's security wing has said 'concerns have been raised in regarding vulnerabilities in ADSL modems, which can be exploited by attackers to implant malwares change configurations or manipulate data.'

An ADSL modem is a version of the regular DSL modem, that gives higher download but lower upload speeds. The security wing has advised that ISP's should ask consumers to change default usernames and passwords after installation and also switch off modems when not in use.

Consumers should also upgrade to latest firmware or software and ISP's should disseminate the message to customers at the time of installation and at regular intervals, the DoT has said while adding that ISP's should disable protocol ports on the modems which otherwise may be used as hacking points to plant malwares. Customers have also been advised to check daily usage online and alert the internet service provider if usage appears to be unexpected. DoT has asked service providers to issue immediate advisories to new customers and alert all existing customers through email or phone calls, within two months.